Paraffin wax compositions



Patented Apr. 21, 1953 2,636,004 PARAFFIN WAX COMPOSITIONS Robert G. Capell, William Rideniiui', anli John ewa t Pitt u 3 i i q 19. Gu

Researclra Development Company, Pittsburgh;

Pa., a corporation of Delaware No Drawing; Applicatio'ii Jane 7, 1950; Serial No. 166,764 15 Claims. (01. 252-52) This invention relates to improved paraffin wax compositions, and more particularly to improved paraflin wax compositions stabilized against oxidative and analogous forms of deterioration resulting from subjecting paraflin wax to elevated temperatures, air and the like.

The methods of separating parafiin wax from crude petroleum products, such as by distillation, chilling with filtering or centrifuging, sweating, and solvent extraction, are well known. Various methods of paraflin wax purification, such as treatment with sulfuric acid and fullers earth, are also well known. Although this purification helps to produce parafiin waxes initially free from odor, taste, and color, it is not effective enough to prevent subsequent oxidative deter-ioration which has been troublesome to industrial users of paraffin wax.

One of the most widely practiced applications of paraffin wax is in the coating industry wherein hot wax baths are employed for waterproofing, treating, impregnating or sizing paper and similar products, and wherein wax is employed to provide a protective coating for materials of all kinds. More specifically, the use of hot liquefied wax is widely practiced in" the manufacture of such articles as waxed paper,- esp'ecially waxed bread wrappers, waxed milk cartons and other beverage containers, cartons, bottle caps, shot shell tubes, matches, wax impregnated fabrics, paper-metal foil electrical condensers, junction and terminal boxes, transformers, wax impregnated insulation; coils and windings, candles; as well as a host of other products too numerous to mention.

In each instance where ah'ot bath of liquified paraffin wax is employed, problems of wax decomposition must be dealt with. This decomposition, which is generally considered to be the result of an oxidative mechanism, is evidenced by the appearance of undesirable odors, discoloration of the wax, and the formation of or ganic acids, peroxides, and possibly anhydrides and lactones in the wax; Thus, suppliers of refined parafiin wax generally recommend that the temperature of a wax melt be kept below 160 F. (71 C.) because, beginning at about this temperature, decomposition starts, accompanied by the development of an acroleinic or burnt odor, a similar taste and a darkening of the color. Paraflin waxes ranging in melting point from 59 F. (15 C.) to 176 F. C.) having from fifteen to thirty-five straight chain carbon atoms are readily oxidized in' contact with air above 160 F. By way of example, after 50 hours at 200 F. a paraffin wax having a melting point of 122 F. begins to show traces of peroxides, and after hours at 212 F. a titratable amount of fatty acid has developed.

Besides the formation of objectionable odors and an increase in color and acidity, oxidation brings about a lowering of melting point and tensile strength, and an overall deterioration of valuable properties, such as hardness and the like, of the wax. Moreover, when decomposition occurs, much wax is lost through volatilization and the periodic purification steps necessitated by this decomposition. Consequently, it is of considerable importance to improve the heat stability of paraflin wax.

Wax compositions of improved heat stability, moreover, offer many processing advantages. Wax coating and impregnating baths may be operated safely at higher temperatures to chest improved penetration, while allowing better control over the amount of wax pick-up by the paper or other stock being treated. In addition, entirely new applications, previously eliminated from consideration because of temperature limitations, become practicable for waxes having improved heat stability. Furthermore, tank cars may be unloaded more rapidly because higher temperatures resulting in lower viscosities give better transfer of heat and flow, making possible savings in labor and steam costs.

A further problem encountered by users of paraffin wax is that of providing a finished prodnot, such as waxed paper and. beverage containers; which will not deteriorate or discolor upon exposure to air; The salability' of food products in wrappings and containers impregnated with wax is adversely affected by discoloration or yellowing of the wax due to oxidation. This difficulty becomes more acute with the recent emphasis placed on packaging and package design.

It has been proposed to mprove the stability of waxes against oxidative deter oration by incorp ratingwere one or more materials called antioxid'ants' because such materials are believed to inhibit the formation of undesirable products of oxidation. However, the inhibition of paraiiin wax against oxidation presents special difficulties not encountered when choosing an anti-oxidant for other purposes. First, the anti-oxidant material must be capable of withstanding the temperatures employed in wax melts Without loss in anti-oxidant powers. This problem, and. oxidation conditions in general, are accentuated in the blending of paraflin wax with higher melting point materials such as polyethylene, as set forth in copending application Ser. No. 601,556, filed June 25, 1945, by Bowman, Ridenour, and Hollenback and assigned to the same assignee as the present application. The higher temperatures and agitation employed tend to increase oxidation. Accordingly, which are suitable in mild temperature applications may not be suitable in paraffin wax. In addition, an anti-oxidant must not adversely affect the physical properties of the wax.

Where paraffin wax is employed in the manufacture of wrappings, containers, and coatings for foods, an anti-oxidant must not impart color, odor, or taste to the wax, either in the wax melt or when in contact with the food. The standards for parafiin wax are generally much higher than for most other products, including many edible products such as edible fats and oils. This is particularly true with regard to color and odor. Lard oil, for example, has a characteristic odor which although not objectionable from a standpoint of human consumption would be highly objectionable if found in parafiin wax compositions. Any color imparted to parafiin wax is highly objectionable from a marketing standpoint and, therefore, a very small degree of oxidation which might give only a slight off-White cast to the wax is undesirable, whereas in petroleum oils in general and in many food products a slight discoloration goes unnoticed. Parafiin wax is essentially odorless and, therefore, any

odor due to impurity is very easily detected. For

example, oxidation of paraflin wax to such a degree that it has a peroxide number of 0.01 is usually enough to confer a definitely detectable oxidized odor. Such a small amount of oxidation with its attendant odor may go unnoticed in many other substances which have some slight characteristic odor of their own, the characteristic odor tending to mask the oxidized odor. Since paraffin wax is a crystalline material, small amounts of impurities can effect relatively large changes in physical properties such as melting point and tensile strength. Small amounts of impurities in non-crystalline substances will not exert such a noticeable effect.

The essentially completely odorless and tasteless character of parafin wax combined with the fact that the oxidation of paraffinic-type compounds always leads to soluble oxidation products which tend to affect taste and odor make the problem of inhibiting paraffin wax one that is both difficult and unique. The rigid requirements in the trade for paraffin Wax are therefore such that an anti-oxidant for paramn wax must be eifective in very low concentrations Where it will not cause taste or odor by itself, and at the same time it must, in that low concentration, be so effective that the formation of even extremely small amounts of odorand tasteproducing decomposition products is suppressed.

The question of whether or not any material Will satisfactorily function as an anti-oxidant in any medium is quite unpredictable, for antianti-oxidants oxidant action is highly selective and apparently catalytic. It is so selective, in fact, that one cannot predict with any degree of certainty that a material which is a known anti-oxidant for one substance will still perform as a satisfactory anti-oxidant in another medium. For example, it is well known that many phenolic materials are useful as anti-oxidants for various purposes, but a wide variety of these phenolic materials are not suitable as wax anti-oxidants. To illustrate, a number of phenolic compounds, known to possess anti-oxidant properties in other environments have been tested in parafiin wax and found to be unsatisfactory as paraffin wax antioxidants. These compounds are as follows:

2,2-bis- (4-hydroxyphenyl) -propane;

1,1-bisi-hydroxyphenyl) -cyclohexane;

Orthodihydroxybenzene (cathechol);

Metadihydroxybenz'ene (resorcinol);

Bis (2-methoxyphenyl) methane;

2,5-ditertiarybutylhydroquinone;

3-pentadecylphenol;

Bis (2- hydroxy- 3,5- ditertiarybutyl- 6- methylphenyl) methane;

1,1,2,2-tetrakis (2-methyl-4-hydroxy-5-tertiarybutylphenyl) ethane.

Thus, a material which may be found to exhibit anti-oxidant propertieswith respect to other substances, cannot on that basis be expected to exhibit anti-oxidant properties in parafiin wax. Furthermore, it is difiicult to predict that such a material would be otherwise suitable for use in wax compositions. Apparently, the nature of paraifin wax has considerable bearing on the question.

It is therefore an object of our invention to provide new paraffin wax compositions having improved stability against general decomposition or oxidative deterioration.

More specifically, a further object of our in-- vention is to provide new parafiin wax composttions of improved heat stability, such as stability against decomposition in the hot liquefied state.

A still further object of our invention is to provide new para-inn wax compositions having sta-' bility against deterioration due to the action of air Another object of our invention is to provide improved parafiin wax compositions having good color and exhibiting substantially no odor or taste, such that they may be employed in food packaging.

These and other objects are accomplished by the present invention wherein we provide improved parafiin wax compositions comprising a major amount of a refined paraifin wax and a minor amount, sufficient to inhibit oxidative deterioration, of a phenyl ethyl-catechol, preferably an a phenylethyl catechol. The following are illustrative of the phenylethyl catechols:

(1) 1,2 dihydroxy 4 (aphenylethyl) benzene, said compound having the following structural formula:

benzene, said compound having the following structural formula:

FOE one;

and are indicative of'the degree of oxidative breakdown oftlie paraflin wax subjected to oxidation.

A blend was prepared" employing a 122 F., A: s: T; M; meltingpointiparamn wax'and"0i001 per centfby weightof' tlie compound named herein as- 1;2-dihydroxy.-41-(aplieziylethyl)-benzene. Threeliundred gramsof the blend were placed in a glass oxidation cell 'suspenued'in an oil bath maintained'at' 240F L Prehieated; dry air at' a temperature: substantially thev-sa'me as that of the wax was 'passed upwardlyrthrough the molten wax at a controlled minimum-mate of 1'.6"cubic" feet per hour. Once every. 24 hours samples were withdrawn and the oxidation stability of the wax was measured by analyzing for acidity, peroxides; and sapo-Infiable'm'aterial by'methods well known in the'art: Tlieodbhalso was noted;

Table I'shows themesult's obtained along with data on the uninhibited "wax control subjected to the: same test conditions;

Table I Peroxide Number gfigt ggg go mks mg. KOH m Kori wax gm. wax gm. wax Days Oxidized Ooilltrol Collitrol ('Jorlitrol p us 7 1 us 1 us Control 0.001% Control M01 Control 001% Additive Additive Additive 0. 0014 0. 001' 0. '01 0.01" Oil 0. 1 0.0015 0.001 0:01 0.01 0. 1 0. 1 0. 14 0 001 0; 52 0. 01 3. 4 0. 1 0. 32 i 0. 001 4958 0.01 16. 9 0. 1 0. 36 0. 001 17L6 0. 01 43. 0 0. 1 O. 13 0.001 78. 0 0.01 145. 7 0. 1

Other methods of naming these compounds may of course be employed, and, in fact, the compounds in the order as listed are frequently referred. toas phenylethyl catechol number 1, phenylethylcatechol number 2;" and phenylethylcatechol number 3,respectively: The com-'- pounds may be produced-by methodswell knownln the art, and all three .are known,oommercially available compounds.

We have found that'the resistance of parafiin wax to oxidation canbe materially increased, and the temperature to- Which'it may be heatedwith out breakdown can be substantially raisedby addition to the wax of relatively small amounts of a compound'of the class described.

These compounds. can be employed-to advantage in paraffin wax stabilization inamounts ranging from about 0.0001 to 0.1 per cent, by weight, of the wax composition. A preferred range is from about 0.00f0'5't0 0.01 per; cent; byweight, of the wax compositionr Mixtures of the compounds can also beemployed. v

The following illustrative" examples permit further understanding of ourinvention and show the advantageous results'obtained in various wax compositions containingcompounds of the classdescribed. For the purposes of thefO110 W1ng" tests a highly refined paraffin wax having a melting point of 122 F., as determined by A; s:'1*.' M.; method D8'T-42; was employed.- The peroxide: number, neutralization number and saponification numberyreferred to hereinafter; are :all ob-s tained "by means of standard 'iwell known':tests,-

isveryeefiective as an anti-oxi'dant for paraffin.

wax. V

The test employed inExample Twas-performed;

on the compound named hereinias-:l,21-dihydroxy-- 4,5-di-(aphenylethyl) benzeneein a 122 F., A. S.. T. M. melting point, paraffin wax at a concen tration="of anti oxidant of 01001 per" cent by weight. After seven-days at'24O Fi, undercon-' ditions as described above; the sample 'remained. unoxidized as evidenced byftlie absence of odor and relatively unchanged"peroxide; neutraliza= tion and saponification numbers. Table II shows the results obtained as-compared with the uninhibited wax "control. sample subjected to the: same test conditions;

' Table 11' PeroxideNumbai ttitt? iifitt? 1 mg. KOH mg. KOH k wax gm. wax gm. wax Days Oxidized I a I Control Control Control p us p us p 115 Control, 001% Control 0mm) Control 0.001%

' Additive Additive Additive EXAMPLE III as in Example IV, for 60 days, at which time the A' blend was'prepared employing a 122 F., A. S. T. M. meltingpoint, paraffin wax and 0.001 per cent by weight of the compound named herein as 1,2-dihydroxy-3,4.5 -,tri- (aphenylethyl) -benzene. This sample was tested for heat stability as in Example I. After seven days at 240 F., peroxide neutralization and saponification numbers were unchanged from the starting values, as shown in Table III. For purposes of comparison, Table III also includes test data on the uninhibited blank.

numbers, coupled with the lack of odor formation, after subjection of the inhibited parafiin waxes to severe oxidative environment, indicate beyond any doubt that the disclosed compounds are remarkably effective paraffin wax anti-oxi- Table III Neutralization Saponification P 91 Ngmber Number Number is M KOH wax gm. wax gm. Wax

7 Days Oxidized Coilitrol Control Corlitrol us p us .p us Control 5 Control 0.001% Control (LOO-1% Additive Additive Additive 0. 0014 O. 001 0. 01 0. 01 1 0. 1 0. 0015 O. 001 O. 01 0. 01 1 0. 1 0. 14 0. 001 0. 52 0. 01 4 0. 1 0. 32 0. 0 01: 4. 5S 0. O1 9 0. 1 0. 36 0. 001 17. 6 0. 01 0 0. 1 0:13 0. 001 78. 0 0. 01 -1 7 O. 1

, EXAMPLE IV dants. Furthermore, they are not only effective Another blend was made employing 0.001 per cent by weight of the same anti-oxidant compound used for Example I, that is, 1,2-dihydroxy- -(aphenylethyl) -benzene, added to a 122 F.. A. S. T. M. melting point, paraffin wax. One hundred grams of this composition were placed in a glass tumbler covered with a watch glass in an oven maintained at 180 F. Once every 24 hours the sample was examined for the presence of an oxidized odor. The test was terminated at the end of 60 days, at which time, the sample was still free of oxidized odors. The uninhibited wax control, in the same test, developed a strong oxidized odor in from 1 to 4 days, showing that the additive was very'efiective even at the very low concentration employed.

EXAMPLE V A paraffin wax blend was prepared employing 0.001 per cent by weight of 1,2 -dihydroxy-4,5-di-. (aphenylethyD-benzene and tested at 180 F. in a glass tumbler, as in Example IV, for 60 days, at which time the sample was still free of oxidized odor; 7

EXAMPLE VI 'A similar blend containing 0.001 per cent by weight of 1,2-dihydroxy-3,4=,5.-tri-(aphenylethyl)ev 75 ingredients blended therewith to improve other benzene was tested at 180 F. in a glass tumbler,

for inhibiting oxidation of paraffin wax in the hot liquefied condition, but since the anti-oxidant is retained by the wax in the finished wax treated 0 product, the anti-oxidant continues thereafter to perform its desired function, and aids in preventing subsequent deterioration of the parafiin wax due to adverse conditions of heat, air and the like.

Thepotency as paraffin wax anti-oxidants of the compounds disclosed herein permits of the employment of hot baths containing the inhibited paraffin waxes of this invention. In employing such baths, it is not necessary to use a parafiin wax already containing the antioxidants of this invention, but the anti-oxidant can be added in suitable amount to the molten parafiin wax in the bath in order to prevent the oxidative deterioration thereof.

Since the anti-oxidants of this invention can be employed so effectively in relatively small amounts, they do not affect the odor and taste of the paraffin waxes with which they are incorporated. and similarly, none of the desirable physical properties of the wax, such as melting point and tensilestrength, are adversely affected.

As will be understood by those skilled in the art, the stabilized parafiin wax compositions of our invention may contain other additives and characteristics, such as tensile strength, sealing strength, etc., of the composition.

While our invention has been described above with reference to various specific examples and embodiments, it will be understood that the invention is not limited by such examples and embodiments, but that resort may be had to such modifications and variations as fall within the spirit of the invention and the scope of the appended claims.

We claim:

1. An improved wax composition comprising a major amount of a parafiin wax and a minor amount, sufficient to inhibit oxidative deterioration, of a phenylethyl catechol.

2. An improved wax composition comprising a major amount of a paraffin wax and a minor amount, sufficient to inhibit oxidative deterioration, of an alpha phenylethyl catechol.

3. An improved wax composition comprising a major amount of a parafiin wax and a minor amount, sufficient to inhibit oxidative deterioration, of a phenylethyl catechol having the following structural formula:

5. An improved wax composition comprising a major amount of a paraffin wax and a minor amount, sufficient to inhibit oxidative deterioration, of a phenylethyl catechol having the following structural formula:

6. The composition of claim 1, wherein the said compound is present in an amount of from about 0.0001 to 0.1 per cent, by weight.

'7. The composition of claim 2, wherein the said compound is present in an amount of from about 0.0001 to 0.1 per cent, by weight.

8. An improved wax composition comprising a major amount of a paraffin wax and from about 0.0005 to 0.01 per cent, by weight, of 1,2- dihydroxyl- (aphenylethyl) -benzene.

9. An improved wax composition comprising a major amount of a paraffin wax and from about 0.0005 to 0.01 per cent, by weight, of 1,2-dihydroxy-4,5-diaphenylethyl) -benzene.

10. An improved wax composition comprising a major amount of a paraiiin wax and from about 0.0005 to 0.01 per cent, by weight, of 1,2- dihydroxy-3,4,5-tri- (uphenylethyl) -benzene.

11. The method of preventing decomposition of a molten paraffin wax bath which comprises maintaining therein, in an amount suificient to inhibit oxidative deterioration, a phenylethyl catechol.

12. The method of preventing decomposition of a molten parafiin wax bath which comprises maintaining therein, in an amount sufficient to inhibit oxidative deterioration, an alpha phenylethyl catechol.

13. The method of preventing decomposition of a molten parafiin wax bath which comprises maintaining therein from about 0.0005 to 0.01 per cent, by weight, of 1,2-dihydroxy-4-(aphenylethyl) -benzene.

14. The method of preventing decomposition of a molten paraffin wax bath which comprises maintaining therein from about 0.0005 to 0.01 per cent, by weight, of 1,2-dihydroxy-4,5-di- (aphenylethyl) -benzene.

15. The method of preventing decomposition of a molten parafiin wax bath which comprises maintaining therein from about 0.0005 to 0.01 per cent, by weight, of 1,2-dihydroxy-3,4,5-tri- (aphenylethyl) -benzene.

ROBERT G. CAPELL. WILLIAM P. RIDENOUR. JOHN A. STEWART.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,942,827 Mills et al Jan. 6, 1934 1,945,521 Downing et al. Feb. 6 1934 2,044,318 Mills et al June 161, 1936 OTHER REFERENCES Phenolic anti-oxidants for paraffinic materials, Morawetz Industrial and Eng. Chem., July 1949, pp. 1442-1447. 

1. AN IMPROVED WAX COMPOSITION COMPRISING A MAJOR AMOUNT OF A PARAFFIN WAX AND A MINOR AMOUNT, SUFFICIENT TO INHIBIT OXIDATIVE DETERIORATION, OF A PHENYLETHYL CATECHOL. 